The redisign used for new.reddit.com doesn't give moderators as much control, much to the displeasure of many of us who have been on the platform for a long time.

Although I dislike it when people significantly change UI controls.

I always have custom CSS disabled for all subs. The designs are amusing, some are well done, and it's nice that people put effort into designs. However, as I was saying it makes for a terrible and confusing UI experience. Also some designs are intentionally jarring or annoying, and themes often omit elements.

I can't think of any CSS styles that are actually outright bad, though, unless it's intentional (like with /r/crappydesign or /r/ooer).

Just the inconsistency makes it very unusable.

I respectfully disagree for the large part. My own brain seems to have no issue coupling functionality to visual design. Yes it's probably less optimal for novice-to-expert transition than having colour variants, but conversely it also gives stronger immediate affordance as to what subreddit you're using..

It might depend on one's browsing habits. True, I believe the intention was to give subs their own identity, as if they were individual websites. However, I frequently click between subs. The fact is that it's a single website.

I have no question that every study of user interface ever published would indicate that buttons changing visual appearance, position, or availability with no predictability several times in a browsing session is a high friction interface.